BTU challenged?

[scoly]

Am doing my work in one side of a two car garage(~21w x 23d) and heat is becoming a problem. Currently have a 10000 btu window ac that is on a furniture dolly and I place it under the garage door. This leaves a gap around 8' wide x 2' high that I block off with loose cardboard. A lot of hot air gets by. Ceiling is not insulated (Has attic flooring which will make it difficult to do) and neither is the outside wall. Will be cutting a hole in the wall soon but would like to cut it to fit the unit and am not sure if what I have will be sufficient to cool the room. Should I:
1. Cut the hole and install the 10k unit knowing it will cool the space once the door closes all the way?
2. Insulate wall and ceiling and install present unit?
3. Buy a larger unit, install in wall?
Thanks for any suggestions.
Steve

[Jim-Iowa]

It was 92 here yesterday. I have no airconditioner in the shop but my shop has all walls insulated and foam ceiling(it is 1 1/2 stories for attic) temp in the shop with window fan was 82 degrees.
bearable as long as air is moving.
I have noticed 10 degrees diff(cooler in summer & warmer in winter).
So I can`t be more convinced that insulation is very important!!

If it were me I would insulate and install the one you have.
I would have done the same but gave my air conditioner to my son for the babys room. I`ll get another but since I have no heat either

(needed in Iowa) I am considering a Hotel Heater/Air Conditioner.

[gmack5]

Steve,
Several years ago I bought a house in Chicago with an oversized 2-car garage attached with one wall common to the house.

The first thing I did was to insulate the entire garage, all three exposed walls, the ceiling AND the garage door (I put 3" of Styrofoam insulation on the inside of the garage door). Walls were insulated to R-13, Ceiling was R-40 and the garage door had an R factor of 15.

I kept it above 55 degrees in the Chicago winters with a 1600 watt electric heater.

My vote would be for #2, eventho you have hotter summers in Texas, you can always up-size the Air Conditioner, if that one proves to be too small.

[scoly]

Seems insulation may be the best approach. Thanks for the replies. Even if I got a unit large enough to cool the space as is the electricity cost would be a concern. Insulation will help summer and winter. Should have thought it through more to begin with.
Thanks again,
Steve

[LarryG]

If I understand your current setup, you're cooling the air from about your knees on down. If you can somehow position the a/c unit up high, so the heavier cool air can settle naturally, that alone will make a huge difference in the unit's efficiency.

[Tom Miller]

Ditto what everyone else said, with a small added idea:

Maybe you could install an A/C box in the wall based on the size of the largest unit you think you'll need. Anything smaller could be shimmed to fit.

But definitely insulate first. A close second is to get the cool air off the floor.

If it'll be a while before this happens, I'd replace the cardboard with a single piece of 1.5" to 2" foam insulation cut to fit the opening.

Regards,
Tom

[LCHIEN]

Cold (or heat) is a commodity like water or gas.

Think of your situation like this:
You have a liquid (cold) you are pouring into a leaky bucket (your garage).

The rate at which the lquid comes out is measued in BTU.
The leakier your bucket is defines how full you can ever get the bucket.
Also the amount of cold outside the bucket influeces how fast the cold runs out the bucket.

If you plug all the holes (insulation) then the bucket will hold more cold and you won't have to run the faucet (cold supply) so fast.

In fact, a perfectly insulated room you would only have to cool down once and then never turn onthe AC again(ha).

In sizing ACs BTUs the key factors are first the temperatue difference you need to maintain. Then the area and insulation of the walls and ceilings that are against the outside, and finally the area of the windows and doors (which are the worst leakers of cold or heat).
OPen door or open window? Forget it. Its like a softball-size hole in your bucket.

[monte]

Go for the insulation first and then get the unit mounted in the wall or window. You're leaking ost of it out the garage door at this time. Remember that cool air is heavier than the hot air that's inside the shop. With the unti at floor level you're only cooling the air at the floor.

[scoly]

Lots more good info and suggestions. Have decided to go the insulation route for the immediate and install what I have. Really can't decide on a larger unit till I see what the 10k unit will do under better circumstances.
Thanks to all,
Steve